1. Field of the Invention
This invention is directed to methods of synthesizing libraries of diverse complex isoindole and isoquinoline compounds through the use of a facile intramolecular Diels Alder reaction. The invention is further directed to methods for synthesizing the libraries on solid supports. The invention is further directed to methods for identifying and isolating isoindole and isoquinoline compounds with useful and diverse activities from such libraries.
2. Background
Compounds having biological activity can be identified by screening diverse collections of compounds (i.e., libraries of compounds) produced through molecular biology techniques or synthetic chemical techniques. Such screening methods include methods wherein each member of the library is tagged with a unique identifier tag to facilitate identification of compounds having biological activity or where the library comprises a plurality of compounds synthesized at specific locations on the surface of a solid substrate wherein a receptor is appropriately labeled to identify binding to the compound, e.g., fluorescent or radioactive labels. Correlation of the labeled receptor bound to the substrate with its location on the substrate identifies the binding compound. Using these techniques, the development of efficient high throughput screening has greatly enhanced the pharmaceutical industry""s ability to screen large numbers of compounds for biological activity.
Central to these methods is the screening of a multiplicity of compounds in the library and the ability to identify the structures of the compounds which have a requisite biological activity. Preferably, in order to facilitate synthesis and identification, the compounds in the library are typically formed on solid supports wherein the compound is covalently attached to the support via a cleavable or non-cleavable linking arm. In this regard, libraries of diverse compounds are prepared and then screened to identify xe2x80x9clead compoundsxe2x80x9d having good binding affinity to the receptor.
Pharmaceutical drug discovery relies heavily on studies of structure-activity relationships wherein the structure of xe2x80x9clead compoundsxe2x80x9d is typically altered to determine the effect of the alteration on activity. Alteration of the structure of the lead compounds permits evaluation of the effect of the structural alteration on activity. Thus libraries of compounds derived from a lead compound can be created by including derivatives of the lead compound and repeating the screening procedures. In this manner, compounds with the best biological profile, i.e. those that are most active and which have the most ideal pharmacologic and pharmacokinetic properties, can be identified from the initial lead compound.
Thus, the generation of chemical libraries on and off solid resins have proven to be a valuable resource for the pharmaceutical industry in their endeavors to discover new drugs using high throughput screening techniques. In creating the libraries, the compounds are ideally synthesized in situ in solution phase or on a solid support. However, relatively simple synthetic methods to produce a diverse collection of such derivatives in situ are often not available.
Two particular classes of compounds which would be useful for inclusion in screening libraries are hexahydroisoindole and octahydroisoquinoline derivatives. These classes of compounds are known to possess diverse pharmacological and chemical properties and certain members of these classes of compounds are well known to possess biological activity. The following references, hereby incorporated by reference, report the biological activity of such chemical compounds:
Dondio, Giulio; Clarke, Geoffrey D.; Giardina, Giuseppe; Petrillo, Paola; Petrone, Giuseppe; Ronzoni, Silvano; Visentin, Luciano; Vecchietti, Vittorio. The role of the xe2x80x9cspacerxe2x80x9d in the octahydroisoquinoline series: Discovery of SB 213698, a non-peptidic, potent and selective delta opioid agonist. Analgesia (Elmsford, N. Y.) (1995), 1(4-6), 394-9. CODEN: AALGEB; ISSN: 1071-569X. CAN 124:134781
Clarke, Dondio G.; Giardina, G. D.; Petrillo, P.; Rapalli, L.; Ronzoni, S.; Vecchietti, V. Potent and selective non-peptidic delta opioid ligands based on the novel heterocycle-condensed octahydroisoquinoline structure. Regul. Pept. (1 994), (Suppl. 1), S43-S44. CODEN: REPPDY; ISSN: 0167-0115. CAN 120:260570
Judd, Duncan B.; Brown, Dearg S.; Lloyd, Jane E.; McElroy, Andrew B.; Scopes, David I. C.; Birch, Phillip J.; Hayes, Ann G.; Sheehan, Michael J. Synthesis, antinociceptive activity and opioid receptor profiles of substituted trans-3-(decahydro- and octahydro-4a-isoquinolinyl)phenols. J. Med. Chem. (1992), 35(1), 48-56. CODEN: JMCMAR; ISSN: 0022-2623. CAN 116:41268
Yamaguchi, Toshiaki; Yanagi, Takashi; Hokari, Hiroshi; Mukaiyama, Yuko; Kamijo, Tetsuhide; Yamamoto, Iwao. Preparation and optically active succinic acid derivatives. II. Efficient and practical synthesis of KAD-1229. Chem. Pharm. Bull. (1998), 46(2), 337-340. CODEN: CPBTAL; ISSN: 0009-2363. CAN 128:217248
Commercon, Alain; Lebrun, Alain; Mailliet, Patrick; Peyronel, Jean Francois; Sounigo, Fabienne; Truchon, Alain; Zucco, Martine; Cheve, Michel. New benzisoindole derivatives as inhibitors of farnesyl transferase, their preparation, and pharmaceutical compositions containing them. Fr. Demande, 96 pp. CODEN: FRXXBL. FR2736641 A1 19970117. CAN 127:95194
Hecker, Scott J.; Jefson, Martin R.; McFarland, James W. Preparation of derivatives of rosaramicin, repromicin, 5-mycaminosyltylonide, desmycosin, lactenocin, O-demethyllactenocin, cirramycin A1, and 23-deoxymycaminosyltylonide as antibacterials and antimycoplasmics. U.S., 22 pp. Cont.-in-part of U.S. Ser. No. 996,243, abandoned. CODEN: USXXAM. U.S. Pat. No. 5,545,624A 19960813. CAN 125:248316
Steiner, Gerd; Munschauer, Rainer; Unger, Liliane; Teschendorf, Hans-Juergen; Hoeger, Thomas. Preparation of N-substituted bridged 4,7,8,9-tetrahydroisoindoline derivatives as drugs. Ger. Offen., 6 pp. CODEN: GWXXBX. DE4341400 A1 19950608. CAN 123:285768
Kamijo, Tetsukyo; Yanagi, Takashi; Hokari, Hiroshi; Oda, Juko. Preparation of hexahydroisoindoline derivative as antidiabetic agent. Jpn. Kokai Tokkyo Koho, 6 pp. CODEN: JKXXAF. JP 06340622 A2 19941213 Heisei. CAN 122:213925
Kamijo, Tetsukyo; Yanagi, Takashi; Hokari, Hiroshi; Oda, Juko. Preparation of hexahydroisoindoline derivative as antidiabetic agent. Jpn. Kokai Tokkyo Koho, 6 pp. CODEN: JKXXAF. JP 06340623 A2 19941213 Heisei. CAN 122:187390
Ohnota, Hideki; Kobayashi, Miho; Koizumi, Takashi; Katsuno, Kenji; Sato, Fumiyasu; Aizawa, Toru. In vitro insulinotropic action of a new non-sulfonylurea hypoglycemic agent, calcium (2S)-2-benzyl-3-(cis-hexahydro-2-isoindolinylcarbonyl)propionate dihydrate (KAD-1229), in rat pancreatic B-cells. Biochem. Pharmacol. (1995), 49(2), 165-71. CODEN: BCPCA6; ISSN: 0006-2952. CAN 122:96220
Accordingly, in order to develop new pharmaceutical drugs to treat various disease conditions, it would be highly desirable to be able to generate libraries of diverse hexahydroisoindole and octahydroisoquinoline derivatives optionally attached to a solid support. There is thus a need for a facile in situ method for the generation of a multiplicity of reduced isoindole and isoquinoline compounds.
This invention is directed to general synthetic methods for preparing hexahydroisoindole, hexahydroisooxyindole and octahydroisooxyquinoline compounds on or off a solid support by employing a mild Diels Alder reaction for the in situ generation of the final compounds. The invention is further directed to the use of these methods to incorporate such reduced isoindole and isooxyquinoline groups in synthetic compound libraries and to libraries containing such compounds.
Hexahydroisoindole, hexahydroisooxyindole, and octahydroisooxyquinoline derivative libraries provided by this invention are synthesized by the Diels Alder cycloaddition reaction of amino acid derived novel triene precursors in accordance with the following general schemes: 
wherein R1 is a standard natural aminoacid side chain; R2 is H, CH3, COOR or CN; R3 is H, alkyl, substituted alkyl, halo, aryl, substituted aryl, butoxycarbonyl (BOC) or carbobenzyloxy (CBz), R4 and R5 are the same or different and are selected from H, benzyl and COOR or R4 and R5 together form an aryl, substituted aryl, cycloalkyl is or a heterocyclic ring, R6 and R7 are the same or different and are selected from H, alkyl, halo or alkoxy; R is selected from H, lower alkyl, or benzyl, X is oxygen or a CH2 bridging group, P is a C1-C4 alkyl group or a solid support resin such as Wang resin, and E is COOP. The carbonyl group of the hexahydroisooxyindole and octahydrooxyquinoline carbonyl compound can optionally be reduced or not introduced to provide the hexahydroisoindole and octahydroisoquinoline derivatives.
The amino acid derived novel triene precursors of Formulas I, Ixe2x80x2, III, IIIxe2x80x2, V, Vxe2x80x2, and VII above are another aspect of the invention.
The standard amino acid side chain for R1 may be selected from any of the known natural amino acid groups such as alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, isoleucine, glycine, leucine, histidine, methionine, lysine, phenylalanine, proline, serine, valine, threonine, tryptophane, tyrosine, and the like.
In one embodiment of this invention, the amino acid derived novel triene precursors are covalently attached to a solid support. Solid supports containing such amino acid derived novel triene precursors derivatives may comprise a linking arm which links the solid support to the triene precursor. The linking arm can be either cleavable or non-cleavable. The novel triene precursors attached to the solid support can be used to prepare a library of either solid phase or soluble hexahydroisoindole, hexahydroisooxyindole or octahydroisooxyquinoline derivatives.
The methods described above can be used to create a library of diverse isoindole and isoquinoline derivatives. Accordingly, in one of its composition aspects, this invention is directed to a library of diverse isoindole and isoquinoline derivatives comprising a plurality of solid supports having a plurality of covalently bound isoindole and isoquinoline derivatives, wherein the isoindole and isoquinoline derivative bound to each of said supports is substantially homogeneous and further wherein the isoindole and isoquinoline derivative bound on one support is different from the isoindole and isoquinoline derivatives bound on the other supports. The library is screened to isolate individual compounds that bind to a receptor or possess some desired property.
Accordingly, in one of the embodiments, the invention is directed to a method for synthesizing a plurality of hexahydroisoindole, hexahydroisooxyindole or octahydroisooxyquinoline compounds covalently attached to a solid support which comprises:
a) selecting a solid support comprising at least one compound attached thereto which compound comprises a triene moiety selected from those of the formula: 
xe2x80x83wherein W is Oxygen or hydrogen, q is an integer from zero to one, Y is an oxygen or CH2 bridging group or is H at each carbon atom and R1 to R5 and P are as recited above, and,
b) converting said triene moiety to the corresponding hexahydroisoindole, hexahydroisooxyindole or octahydroisooxyquinoline moiety by a Diels Alder cycloaddition reaction.
Preferred compounds within the scope of those listed above for formulae I-VII include those compounds wherein R1 is a standard natural amino acid side chain; R2 is H, CH3, COOR or CN; R3 is H, benzyl, substituted benzyl, butoxycarbonyl (BOC) or carbobenzyloxy (CBz), R4 and R5 are the same or different and are selected from H, benzyl and COOR or R4 and R5 together form a saturated or unsaturated carbocyclic ring of 5 or 6 ring atoms or a saturated or unsaturated heterocyclic ring having 5 or 6 ring atoms and 1,2 or 3 hetero atoms selected from nitogen, oxygen and sulfur atoms; R is selected from H, lower alkyl, or benzyl, X is absent or is an oxygen or a CH2 bridging group and P is a C1-C4 alkyl group or a solid support resin such as Wang resin.
Most preferred are those compounds wherein R1 is a standard natural aminoacid side chain; R2 is H, CH3, COOR or CN; R3 is H, benzyl, butoxycarbonyl (BOC) or carbobenzyloxy (CBz), R4 and R5 are the same or different and are selected from H, benzyl and COOR or R4 and R5 together form a saturated or unsaturated carbocyclic ring of 5 or 6 ring atoms or a furan ring; R is selected from H, lower alkyl, or benzyl, X is absent and P is a C1-C4 alkyl group or a solid support resin such as Wang resin.
Listed below are definitions of various terms used to describe this invention. These definitions apply to the terms as they are used throughout this specification, unless otherwise limited in specific instances, either individually or as part of a larger group.
The term xe2x80x9calkylxe2x80x9d refers to straight or branched chain unsubstituted hydrocarbon groups of 1 to 20 carbon atoms, preferably 1 to 7 carbon atoms. The expression xe2x80x9clower alkylxe2x80x9d refers to unsubstituted alkyl groups of 1 to 4 carbon atoms.
The term xe2x80x9csubstituted alkylxe2x80x9d refers to an alkyl group substituted by, for example, one to four substituents, such as, halo, trifluoromethyl, trifluoromethoxy, hydroxy, alkoxy, cycloalkyoxy, heterocylooxy, oxo, alkanoyl, aryloxy, alkanoyloxy, amino, alkylamino, arylamino, aralkylamino, cycloalkylamino, heterocycloamino, disubstituted amines in which the 2 amino substituents are selected from alkyl, aryl or aralkyl, alkanoylamine, aroylamino, aralkanoylamino, substituted alkanoylamino, substituted arylamino, substituted aralkanoylamino, thiol, alkylthio, arylthio, aralkylthio, cycloalkylthio, heterocyclothio, alkylthiono, arylthiono, aralkylthiono, alkylsulfonyl, arylsulfonyl, aralkylsulfonyl, sulfonamido (e.g. SO2NH2), substituted sulfonamido, nitro, cyano, carboxy, carbamyl (e.g. CONH2) substituted carbamyl (e.g.CONH alkyl, CONE aryl, CONH aralkyl or cases where there are two substituents on the nitrogen selected from alkyl, aryl or aralkyl), alkoxycarbonyl, aryl, substituted aryl, guanidino and heterocyclos, such as indolyl, imidazolyl, furyl, thienyl, thiazolyl, pyrrolidyl, pyridyl, pyrimidyl and the like. Where noted above where the substituent is further substituted it will be with halogen, alkyl, alkoxy, aryl or aralkyl.
The term xe2x80x9chalogenxe2x80x9d or xe2x80x9chaloxe2x80x9d refers to fluroine, chlorine, bromine and iodine.
The term xe2x80x9carylxe2x80x9d refers to monocyclic or bicyclic aromatic hydrocarbon groups having 6 to 12 carbon atoms in the ring portion, such as phenyl, napthyl, biphenyl and diphenyl and diphenyl groups, each of which may be substituted.
The term xe2x80x9caralkylxe2x80x9d refers to an aryl group bonded directly through an alkyl group, such as benzyl.
The term xe2x80x9csubstituted arylxe2x80x9d refers to an aryl group substituted by, for example, one to four substituents such as alkyl; substituted alkyl, halo, trifluoromethoxy, trifluoromethyl, hydroxy, alkoxy, cycloalkyloxy, heterocyclooxy, alkanoyl, alkanoyloxy, amino, alkylamino, aralkylamino, cycloalkylamino, heterocycloamino, dialkylamino, alkanoylamino, thiol, alkylthio, cycloalkylthio, heterocyclothio, ureido nitro, cyano, carboxy, carboxyalkyl, carbamyl, alkoxycarbonyl, alkylthiono, arylthiono, alkysulfonyl, sulfonamido, aryloxy and the like. The substitutent may be further substituted by halo, hydroxy, alkyll, alkoxy, aryl, substituted aryl, substituted alkyl or aralkyl. xe2x80x9cSubstituted bemzylxe2x80x9d refers to a benzyl group substituted by, for example, any of the groups listed above for substituted aryl.
The term xe2x80x9ccycloalkylxe2x80x9d refers to optionally substituted, saturated cyclic hydrocarbon ring systems, preferably containing 1 to 3 rings and 3 to 7 carbons per ring which may be further fused with an unsaturated C3-C7 carbocyclic ring. Exemplary groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl, cyclododecyl, and adamantyl. Exemplary substituents include one or more alkyl groups as described above, oe one or more groups described above as alkyl substitutents.
The terms xe2x80x9cheterocyclexe2x80x9d, xe2x80x9cheterocyclicxe2x80x9d and xe2x80x9cheterocycloxe2x80x9d refer to an optionally substituted, fully saturated or unsaturated , aromatic or nonaromatic cyclic group, for example, which is a 4 to 7 membered monocyclic, 7 to 11 membered bicyclic, or 10 to 15 membered tricyclic ring system, which has at least one heteroatom in at least one carbon atom-containing ring. Each ring of the heterocyclic group containing a heteroatom may have 1, 2 or 3 heteroatoms selected from nitrogen atoms, oxygen atoms and sulfur atoms, where the nitrogen and sulfur heteroatoms may also optionally be oxidized and the nitrogen heteroatoms may also optionally be quaternized. The heterocyclic group may be attached at any heteroatom or carbon atom.
Exemplary monocyclic hetrerocyclic groups include pyrrolidinyl, pyrrolyl, indolyl, pyrazolyl, oxetanyl, pyrazolinyl, imidazolyl, imidazolinyl, imidazolidinyl, oxazolyl, oxazolidinyl, isoxazolinyl, isoxazolyl, thizaolyl, thiadiazolyl, thiazolidinyl, isothiazolyl, isothiazolidinyl, furyl, tetrahydrofuryl, thienyl, oxadiazolyl, piperidinyl, piperazinyl, 2-oxopiperazinyl, 2-oxopiperidinyl, 2-oxopyrrolidinyl, 2-oxazepinyl, azepinyl, 4-piperidonyl, pyridyl, N-oxo-pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, tetrahydropryanyl, tetrahydrothiopyranyl, tetrahydrothiopyranyl sulfone, morpholinyl, thiomorpholinyl, thiomorpholinyl sulfoxide, thiomorpholinyl sulfone, 1,3-dixolane and tetrahydro-1,1-dioxothienyl, dioxanyl, isothiazolidinyl, thietanyl, thiiranyl, triazinyl, and triazolyl, and the like.
Exemplary bicyclic heterocyclic groups include benzothiazolyl, benzoxazolyl, benzothienyl, quinuclidinyl, quinolinyl, quinolinyl-N-oxide, tetrahydroisoquinolinyl, isoquinolinyl, benzimidazolyl, benzopyranyl, indolizinyl, benzofuryl, chromonyl, coumarinyl, cinnolinyl, quinoxalinyl, indazolyl, pyrrolopridyl, furopyridinyl (such as furo[2,3-c]pyridinyl, furo[3,1-b]pyridinyl), or furo[2,3-b]pyridinyl), dihydroisoindolyl, dihydroquinazolinyl (such as 3,4-dihydro-4-oxo-quinazolinyl), benzisothiazolyl, benzisoxazolyl, benzodiazinyl, benzofurazanyl, benzothiopyranyl, benzotriazolyl, benzpyrazolyl, dihydrobenzofuryl, dihydrobenzothienyl, dihydrobenzothiopyranyl, dihydrobenzothiopyranyl sulfone, dihydrobenzopyranyl, indolinyl, isochromanyl, isoindolinyl, naphthyridinyl, phthalazinyl, piperonyl, purinyl, pyridopyridyl, quinazolinyl, tetrahydroquinolinyl, thienofuryl, thienopyridyl, thienothienyl, and the like.
Exemplary substituents include one or more alkyl groups as described above or one or more groups described above as alkyl substituents.
The term xe2x80x9cheteroatomsxe2x80x9d shall include oxygen, sulfur and nitrogen.
Throughout this specification, certain abbreviations are employed having the following meanings, unless specifically indicated otherwise. DMF is N,N-dimethyl, formamide, MeOH is methanol, THF is tetrahydrofuran, DIEA is diisopropylethylamine, HATU is O-(7-azabenzotriazol-1-y1)-1,1,3,3-tetramethyluroniumhexafluorosulfate, BOC is butoxycarbonyl, CBZ is carbobenzyloxy, DME is ethylene glycol dimethyl ether.
The generation of chemical libraries on and off resin has proven to be a valuable resource for the pharmaceutical industry in their endeavors to discover new drugs from High Throughput screening. The current invention provides an invention process which allows for the assembly of highly complex drug like molecules with or without defined stereochemistry in 4-5 steps. The key step of this invention is a remarkably facile Intramolecular Diels Alder reaction which allows this complex system to be assembled with regio, stereo and facial selectivity.
In accordance with the invention, novel amino-acid derived triene precursors are prepared, on or off a solid support. These triene precursors undergo a Diels Alder cycloaddition reaction in situ, to yield the complex isoindole, isooxyindole and isooxyquinoline compound libraries of the invention.

The initial step in the invention involves the acylation of the ester 1 either on or off a solid support with the acid chloride 2. A consists of an appropriate solvent and 1 equivalent of base at from 0-40 C. 
The second step involves the Diels Alder reaction to generate 4. In some cases the reaction of 3 to 4 is so facile that 3 is not isolated. B represents an appropriate solvent such as methylene chloride, an appropriate temperature such as 0-110xc2x0 C., and the reaction time is 1-64 hours. The reaction temperature and solvent helps determine the product ratios of the cis and trans ring juncture.

The second part of this invention involves the assembly of the hexahydroisoindole 7. This proceeds through D which represents a reductive amination of 1 with the aldehyde 5 and an appropriate reducing agent such as sodium cyanoborohydride. It then involves the introduction of R3 which in the best cases is a benzoyl or substituted benzoyl group, but can also be other groups such as benzyl, substituted benzyl, BOC, CBz or Tosyl. The introduction of the benzoyl group significantly accelerates the Diels Alder reaction.
The third process in this invention involves the thermal Diels Alder where C: is the appropriate solvent such as toluene, xylene, DMF, water or DME; the appropriate temperature such as 80-120xc2x0 C. and the appropriate reaction time. 
A favored thermal or Lewis acid-catalyzed Diels-Alder reaction normally requires an electron deficient dienophile and an electron-rich diene ([2+4] cycloadditions), or in the case of inverse electron-demand, an electron-rich dienophile and an electron-deficient diene ([4+2] cycloadditions). It is believed that if both the diene and dienophile have the same electron character, i.e., both electron-rich or both electron-deficient, the Diels-Alder reaction is expected only under forcing conditions.
During our studies on Diels-Alder reactions of novel amino acid-derived triene precursors, we found that the cycloaddition proceeds under surprisingly mild thermal conditions between a diene bearing an amide carbonyl group and a dienophile conjugated to an ester carbonyl group. Our observation of mild thermal Diels-Alder cycloadditons that do not have complimentary electron-demand between dienes and dienophiles is unexpected.
The compounds comprising the triene precursor moiety can optionally be covalently attached directly to a solid support or can be attached via a linking arm. The solid support is a material having a rigid or semi-rigid surface which contains or which can be derivatized to contain a reactive functionality which covalently links a compound to the surface thereof. Such materials are well known in the art and include, by way of example, silicon dioxide supports containing reactive Sixe2x80x94OH groups, polyacrylamide supports, polystyrene supports, polyethylene glycol supports and the like. Such supports will preferably take the form of small beads, pellets, disks, or other conventional forms. Linking arms for attaching the triene precursor to the solid support are well known in the art and include, for example, ester, amide, carbamate, ether, thio ether, urea, amine groups and the like.
In those embodiments where a linking arm is employed, the attachment to the solid support is readily cleavable by specific chemical reactions to provide the hexahydroisoindole, hexahydroisooxyindole and octahydroisooxyquinoline compounds free of the solid support. The chemical reactions employed to cleave the attachment to the solid support are selected so as to be specific for the cleavage of the attachment while preventing unintended chemical reactions occurring elsewhere on the compound. For example, where a Wang resin is used as the solid support, trifluoroacetic acid is used to wash the compound from the solid support.
The hexahydroisoindole or octahydroisooxyquinoline compounds which may be prepared by the method of the present invention and which comprise the compounds of the libraries of the invention include those compounds of the formulae II, IIxe2x80x2, IV, IVxe2x80x2, VI, VIxe2x80x2 and VIII above.